[parasubvert]

SOA doesnt have to imply an ESB, true, but it usually did in practice. I too worked with Sonic , IBM broker, Mule, but mostly BEA WebLogic and AquaLogic. What was often missing in popular SOA was services-oriented delivery, where the unit of deployment was independently evolvabke from others. It was more focused on interface modularity for some future implementation decomposition of the monolith. It fulfilled half the problem.

Microservices have been enabling a new generation to accomplish this decomposition through by focusing on services oriented delivery and deployment, and by dramatically constraining the protocols to HTTP, maybe some pub/sub or gRPC, not likely many others (and thus no distributed transactions, simpler QoS levels, etc).